Windows only: Freeware notification utility Big Stretch Reminder prompts you at regular intervals to get off the PC and take a break—a handy way to help prevent RSI, or just give your mind a break.

Once you've installed the utility, you can head into the settings to change the reminder message from random tips to a specific message, or change the frequency of the alerts. If you're looking for a more full-featured solution to your RSI issues you might want to check out previously mentioned WorkRave instead, but this utility works well—or you could always use it as a custom reminder for something else. Big Stretch Reminder is a free download for Windows only.